Fix test TestPatternBoundedQueuing that gets stuck

"main" #1 prio=5 os_prio=0 tid=0x00007fa13000b000 nid=0x6f32 waiting on condition [0x00007fa138ac9000]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x00000000f8df23a8> (a java.util.concurrent.CompletableFuture$Signaller)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
        at java.util.concurrent.CompletableFuture$Signaller.block(CompletableFuture.java:1693)
        at java.util.concurrent.ForkJoinPool.managedBlock(ForkJoinPool.java:3323)
        at java.util.concurrent.CompletableFuture.waitingGet(CompletableFuture.java:1729)
        at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
        at org.nuxeo.lib.stream.tests.pattern.TestPatternBoundedQueuing.producerAndBuggyConsumers(TestPatternBoundedQueuing.java:154)